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UNITED STAiIlES PATENT orinon.

LUDWIG HEINRICH REUTER, OF NEW YORK, N. Y., ASSIGNOR TO BASIC CHEMICAL COMPANY, OF NEI'V YORK, N. Y., A CORPORATION OF NEW YORK.

SOAP.

Specification of Letters Patent.

Patented Sept. 4, 1906.

Application filed February 19,1906. Serial No. 301,908,

To all whom it may concern:

Be it known that I, Lunwio HEINRICH REUTER, a subject of the King of Bavaria, and a resident of the city of New York, borough of Biooklyn, in the county of Kings and State of New York, have invented a new and Improved Soap, of which the following is a full, clear, and exact description.

My invention relates to a liquid soap or soap solution for toilet and medicinal purposes and for use in the arts I have discovered that @llm) or soap solution of a very supe riUF ETELfi-dter is obtained if to a liquid soap a salt of perboric acid is added; but Ihave found that it will not be sufficient to simply dissolve a salt of perboric acid in the soap. The resulting product would not be stable. It would contain too much free alkali and could not be used, therefore, for toilet or medicinal purposes; neither could it be used for the cleansing and bleaching of textiles and fabrics, of feathers, straw goods, and the like, because the free alkali would loosen or destroy the fine fibers of delicate fabricsas, for instance, silk or laces. It would have a keratolytic or horn-dissolving effect on valuable feathers as, for instance, ostrichfeathersand would, finally, color straw goods yellowish to brown instead of making them whiter. N ow I have found that the opinion propagated by manufacturers of perboratesnamely, that a solution of perborate is weakly alkaline, almost neutral, and that it is, furthermore, absolutelynon-caustic and nontoxicdoes not agree with the facts. Indeed, I have found that salts of perboric acid produce on being dissolved in water quite a quantity of caustic soda, and the results I have obtained in determining the alkalinity of perborate solutions show that the following reaction takes place on dissolving, for instance, sodiunrwborate in water:

viz: one hundred parts of sodium perborate yield on dissolving in water not less than thirteen parts of caustic soda. That the use of such a strongly-alkalineliquid for all purposes mentioned above, especially, also, for the teeth if added to a mouth-wash, would be injurious and dangerous is evident. As a matter of fact such a solution would develop caustic and irritating properties when used for toilet or medicinal purposes and would loosen, destroy, or discolor textile fabrics, feathers, straw goods, and the like. N ow I have found that for the purpose of neutralizing the free caustic alkali any organic or inorganic acid can be used and that boric acid (ILBQQ is the most suitable in cases where the presence of five to six per cent. of alkali borate is not objectionable in the finished liquid soap. Wherever so much alkali borate is not desired, any other acid can be used, and in a series of experiments I have used with good results, of organic acids, acetic, formic. and lactic acid, and of inorganic 2101(5, or instance, 1 drochloric and sulfuric acid. The

last two acids rave to be properly diluted wit-h water and added slowly, drop by drop, well stirring all the time, to the soap solution containing the hydrolytic products of perboratenamely, hydro en pepogtid, alkali borate, and free caustic alkali. If that is not done, the liquid becomes warm, and a loss of hydrogen peroxid will be the result.

As an example of manufacture, I saponify oils and fats, preferably those containing olein with an alkali-forinstance, caustic potash1n the usual way and dissolvetlhrty to "forty pounds of the finished soap, which has an alkaline reaction, in about twelve gallons of water or in a mixture of water and lycerin or any other alcohol. I allow then the 1quid to settle and filter, finally, in the usual way, preferably under pressure by means of a filter-press. To the clear liquid soap thus obtained I add in small portions at a time the required quantity of a salt of perboric acidsay, for instance, five pounds of )otas si u n LI) CE ii/6SlOWlY stirring the llQL III F during 1e process of dissolving, which takes between one and two hours. Care must be taken to keep the temperature of the liquid as low as possible for the purpose of avoiding as much as possible loss of hydrogen peroxid. As soon as all perborateis properly dissolved I titrate the percentage of free alkali the soap contains and add, while stirring, enough finely-powdered boric acid in small portions to completely neTfiraliZThe free alkali. I have found in one experiment that one hundred pounds of perborated liquid soap contained 1.2 pounds of caustic potash, and it required 1.5 pounds of boric acid to neutralize it.

The finished soap manufactured as above described is a practically neutral almost colorless liquid of oily appearance containing the hydrolytic products of perborate namely, in one hundred grams of the liquid soap 0.5 grams of active oxygen in the form of hydrogen peroxid and 5.9 parts of alkali bora-te, of which 3.5 parts were formed by the hydrolysis of the perborate, while the balance of 2.4 parts was the result of the neutralization of the free caustic alkali with boric acid.

The presence of 5.9 per cent. of alkali borate is not objectionable in any case where liquid soap is used. An oxygenated neutral liquid soil-p containing five to six per cent. alkali borate would be valuable for physicians and dentists, as well as for cleaning delicate textiles and fabrics. ()n the other hand, a mere solution of perborate containing a large amount of free alkali would be objectionable. Also the hydrogen-peroxid water of the market is a very poor preparation, because it contains free acids, and for that reason its use is not recommendable for many purposes.

I do not wish to limit myself to the above proportions, as a liquid soap containing more or'less soap basis or more or less of the hydrolytic products of perborate can be manufactured. As already mentioned, instead of boric acid any other acid can be used to neutralize the free alkalias, for instance, sulfuric acid. In this case the iinished soap will contain, in addition to the alkali borate formed by hydrolysis of the perborate, alkali sulfate. If acetic acid is used, the oxygenated liquid soap would contain, in addition to the alkali borate, alkali acetate.

I have found amt-511mm soap containing hydrogen peroxid and alkali borate -an be obtained neutrall by mixing a liquid soap with concentrated hydrogen peroxid of the market and alkali borate; but the use of such an article would be strongly objectionable on account of the acid character of the hydrogen peroxid of the market, while, on the other hand, an oxygenated and borated liquid soap obtained as described above is more uniform, practically neutral, and absolutely non-toxic and non-poisonous. The new oxygenated liquid neutral soap has the further advantage that it keeps better and is stronger than the hydrogen-peroxid solution of the l nited States plnlrniacoptria, which loses so rapidly in strength that, especially in summer-time, it becomes practically worthless in a few days or weeks.

Having thus described my invention, I claim A method of making soap which consists {in saponiiying oils or fats with an alkali, dissolving the alkaline soap in water and alcohol, allowing the liquid to settle, filtering, adding gradually a predetermined quantity of a salt of perboric acid, stirring the liquid during the process of dissolution, keeping the temperature at a low point, and adding linelv-powdered boric acid in small port ions.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses. V

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\Yitnesses LEIGH Donxntznon, ALBERT E. FAY. 

